My max rating was 2000, now I fell back to 1800, still beating 2300 rated players every now and then. Never got lessons tho. Any advice?
Yes. First you have to figure out what kind of player you are there are 5 basic types... Aggressive (I usually tear these to pieces), Positional (Ones I have a hard time with), Tactical (another type I can have a hard time with if we are in a sequence I am not familiar with), Endgame Specialist (In my better days could handle these well), Hybrid Tactical/Positional (Hardest to master). Once you figure this out, study the most common openings to your style of play.
The most common are Positional and Tactical, positional is the easiest to master IMO, but I know a lot of players that think this is the hardest. It really all depends on how your brain works.... Everyone is different... when I was younger, I didn't have any trouble with the end-game strategy I could think very quickly WAY ahead and track really well all the variations I might see and what to do... this would freak out my competition, and I would win when they lost focus. To be a good end-game player you also have to have a better than average memory... since you really need to master as many opening sequences that you can. They would spend time figured their next move then BOOM I would make my move immediately.. which would cause them to think they made a bad move... when in reality it might have been a good move, but I had already anticipated it... they would slow down... think more, make a move then BOOM, I would do it again... a lot of chess at a high level of play is psychological... you want to mentally and emotionally exhaust a player. But as I am older, my cognitive ability has drastically diminished.
Study sequencing of the most common chess openings first, then modern flank openings, you can Goggle the top ten. I will almost exclusively use the Spanish Opening (I know... boring) and depending on what White does if I play 2nd, will go with a French Defense (Again... yeah I know... boring).... which pretty much makes me boring and typical. I play a conservative game and play to get to the end game, (I am considered an 'End-game Specialist) which is where in my better days would win a lot more than lose. Especially when I played White.... against vey good players, I always tried to play to a draw with Black.
Now a days there are a lot of excellent websites focused on Chess, there are a lot more really good players around then when I was at my peak in the mid-90s to early 2000s. With the quality of competition now, I seriously doubt I would be as good now, even if I was at my peak. The best chess used to be played in Russia, now I have to say it's India and China. A decent website to start is
www.expert-chess-strategies.com. They have some excellent videos that do a great job of analyzing opening moves, and they take the time to to show you would would happen with many possible moves.
Play, play, play... get as much practice as you can. Live tournaments are the best, mostly because you get to spend time with other players and can learn from them by observation. Online tournaments are good too, but IMO they aren't as much fun... but do these as well to get practice. One nice thing about on-line games is that your moves are recorded, so you can go back and look at where you may have gone wrong, or where you just got lucky.
Be patient... and do not get frustrated when things go wrong... have fun and learn from your errors. Always remember the higher up you climb in ability and competition, the more likely your games will end in a draw.
BTW 2000 rating is pretty good, that used to be considered Expert level, and depending on your age and how long you've been play could be outstanding. In my better days I had a Senior master Rating for a few years, but could never get over 2500 to be considered a GM. I have beaten GMs in the past, but they usually took me out in tournaments.